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I have a diy TQ, and UQ of 5 oz apex and have had it down to the upper 30's. and at those temps the TQ was plenty warm and I could probably push it down to below freezing, but was at the the lower limit for the UQ. personally I sleep rather cold.

Ha, it's funny how things work out for different folks. Partially trying to explain my surprisingly good results with a mere 2.5 oz ( literally: I had about 1 sq.yd. of CS XP under me in a short WB Yeti style UQ) insulation, I had theorized that I might not get results quite so good in a TQ, especially compared to down, because the UQ might not drape on and around me as well as down. As opposed to my dif cut UQ, which is pulled snugly against my back and around my shoulders. So I thought maybe I might not be quite as warm on top with a given wt of TQ compared to my UQ, just due to fit and drape. But for you it was just the opposite! Now I have to come up with another theory!

Originally Posted by FLRider

The formula for figuring temperature ratings from CLO values is as follows:

84 - (14 * CLO * X), where the final result is in degrees F, CLO is the CLO value of the material and X is the weight of the insulation in oz/sq yd. Note that this assumes no base layer worn (if there is a full base layer, change the 84* to 70*)

So, for Climashield APEX (CLO value 0.82, per Thru-Hiker), the value would be:

84 - (14 * 0.82 * X)
= 84 - (11.48 * X)

So, 2.5 oz:

84 - (11.48 * 2.5)
= 84 - 28.7
= 55.3*

5 oz:

84 - (11.48 * 5)
= 84 - 57.4
= 26.6* F

7.5 oz:

84 - (11.48 * 7.5)
= 84 - 86.1
= -2.1* F

10 oz:

84 - (11.48 * 10)
= 84 - 114.8
= -30.8* F

Now, below freezing, these calculations break down some. Since moisture accumulation through condensation, as well as drafts, become much more important when the outside temperature is 70*+ different from your skin temperature, the insulation you're using has to be much better fitted than at warmer temperatures. Figure these as "ballpark" temperatures, assuming a "normal" sleeper, perfect humidity, no drafts, and no wind.

Figure on them being within 10* of comfort and you should be pretty close. Hope it helps!

Good to see a formula like this, even if I am at least somewhat surprised by the results at both extremes! So apparently the idea is that 1 CLO is 14*f worth of protection? What is the starting figure of 84 based on?

So I have been warm with 2.5 XP ( CLO .82 per oz), in a WB torso UQ, car camping between 46-49 and 95-98% humidity per nearby weather stations, right next to a lake, no warm base layers. ( https://www.hammockforums.net/forum/...ad.php?t=11090 ) though I was def warm and might could have got a few more degrees. But in order to have some slack built in for field conditions, I decided per this quote from the thread: "So, I think I can safely say that this ~9.5 oz synthetic torso quilt will be bombproof, all by itself, for 55 plus, pretty safe in the field for 50 or maybe even 45( especially with warm sleep clothes like fleece)." According to your formula, 2.5=55, and I said bombproof to 55. So I guess that is right close!

Cannibal has reported using 10 osy CS XP at a bit above zero ( in the snow with no tarp!), at minus 11F and some colder temp of maybe ~ minus 20F? And I think he was always warm enough, if mem serves(no doubt with plenty of base layers plus he sleeps real hot apparently). So maybe the minus 30.8F with 10 oz from your formula is really not all that far off at least for some people?

All of which I really find quite amazing, whether with 2.5 oz or 10 oz per sq.yd. I mean really, can anyone get much warmer with that amount of insulation, or a torso quilt of that total weight ( maybe 18 to 20 oz?). Maybe, a little, but that is still awfully good! CS is great stuff as long as you have room for it.

Apparently, signature that I used from 2006 no longer tolerated so now deleted.

FLRider, your equation explains the wide range of numbers I found. When I read folks talking in the theoretical, I saw the numbers you posted. But actual experiences were far more conservative. (For example, in the 7.5 oz weight, I have jotted down 15°, another said 5oz was good to 40°)

You guys have really helped me figure this out. I think I will go for a 7.5 oz for myself (a warm sleeper) and 10 oz for my friend (cold sleeper), and I think we'll be good to about 15°. But now my UQ is warmer than my TQ, and I'm gonna have to make something to keep me warm up top!

Ha, it's funny how things work out for different folks. Partially trying to explain my surprisingly good results with a mere 2.5 oz ( literally: I had about 1 sq.yd. of CS XP under me in a short WB Yeti style UQ) insulation, I had theorized that I might not get results quite so good in a TQ, especially compared to down, because the UQ might not drape on and around me as well as down. As opposed to my dif cut UQ, which is pulled snugly against my back and around my shoulders. So I thought maybe I might not be quite as warm on top with a given wt of TQ compared to my UQ, just due to fit and drape. But for you it was just the opposite! Now I have to come up with another theory!

Good to see a formula like this, even if I am at least somewhat surprised by the results at both extremes! So apparently the idea is that 1 CLO is 14*f worth of protection? What is the starting figure of 84 based on?

So I have been warm with 2.5 XP ( CLO .82 per oz), in a WB torso UQ, car camping between 46-49 and 95-98% humidity per nearby weather stations, right next to a lake, no warm base layers. ( https://www.hammockforums.net/forum/...ad.php?t=11090 ) though I was def warm and might could have got a few more degrees. But in order to have some slack built in for field conditions, I decided per this quote from the thread: "So, I think I can safely say that this ~9.5 oz synthetic torso quilt will be bombproof, all by itself, for 55 plus, pretty safe in the field for 50 or maybe even 45( especially with warm sleep clothes like fleece)." According to your formula, 2.5=55, and I said bombproof to 55. So I guess that is right close!

Cannibal has reported using 10 osy CS XP at a bit above zero ( in the snow with no tarp!), at minus 11F and some colder temp of maybe ~ minus 20F? And I think he was always warm enough, if mem serves(no doubt with plenty of base layers plus he sleeps real hot apparently). So maybe the minus 30.8F with 10 oz from your formula is really not all that far off at least for some people?

All of which I really find quite amazing, whether with 2.5 oz or 10 oz per sq.yd. I mean really, can anyone get much warmer with that amount of insulation, or a torso quilt of that total weight ( maybe 18 to 20 oz?). Maybe, a little, but that is still awfully good! CS is great stuff as long as you have room for it.

Yep, 1 CLO is 14* F (actually, it's 14* and some small decimal, but 14 is close enough for government work). I got that number from the crunching that someone did on these forums a ways back (I can probably find the thread, if you're really interested) when they converted R-value to CLO.

1 CLO is equal to the insulation that an average male needs to remain warm when unmoving at 70* F (the equivalent of a 50s- or 60s-style wool suit). It was an industry standard for the clothing industry, due to "average" working conditions when A/C became common. So, if you're not wearing a base layer, the formula starts at 84* F. (Note that this matches up pretty well with most folks' experience with hammocks: with no shirt, just a pair of shorts, and no under insulation, most folks are fairly comfy around 80* F; most folks start needing under insulation below 70* when wearing a T-shirt to bed.)

As I mentioned, below freezing, fit, wind, and moisture become much more important than raw CLO value. So, below freezing (and the further down you get, the more it's going to vary), take these numbers with a grain of salt.

Personally, I'd be willing to push a 2.5 APEX quilt to about 45* without any supplemental insulation, but I'm an human space heater when I sleep (I once spent a night in Ocala at a recorded temp of 41* F with nothing under me but a poncho and a crumpled-up space blanket; I was cold but not unable to sleep). So, 55* F would definitely be bombproof for that quilt for most folks.

And warmer temps work better with synthetics, for a couple of reasons: one, the percentage of the total weight of the quilt is much lower than when making one for colder temperatures (meaning that the total difference in weight between down and synth is less, since the shell is a greater percentage of the quilt's weight); and, two, liquid water is much more common at warmer temps, so synthetic insulation's greater (well, unless the new DWR down treatments render this obsolete) resistance to wetting out in very humid conditions is a plus.

Originally Posted by darkbyrd

Thanks to everyone for relating their experiences!

FLRider, your equation explains the wide range of numbers I found. When I read folks talking in the theoretical, I saw the numbers you posted. But actual experiences were far more conservative. (For example, in the 7.5 oz weight, I have jotted down 15°, another said 5oz was good to 40°)

You guys have really helped me figure this out. I think I will go for a 7.5 oz for myself (a warm sleeper) and 10 oz for my friend (cold sleeper), and I think we'll be good to about 15°. But now my UQ is warmer than my TQ, and I'm gonna have to make something to keep me warm up top!

The practical numbers for quilts below freezing, as I mentioned, are much more reliant on fit, humidity, and wind than they are for above freezing. So, there's likely going to be quite a variance there. Also, at those temperatures, you want to be more conservative anyway: screwing up at 50* means an uncomfortable night, assuming you've got the calories and aren't wet; screwing up at -20* means they find your freeze-dried corpse in a week or two.

The practical numbers for quilts below freezing, as I mentioned, are much more reliant on fit, humidity, and wind than they are for above freezing. So, there's likely going to be quite a variance there. Also, at those temperatures, you want to be more conservative anyway: screwing up at 50* means an uncomfortable night, assuming you've got the calories and aren't wet; screwing up at -20* means they find your freeze-dried corpse in a week or two.

Hope it helps!

Helps a bunch, and makes me feel confident in my decision. These will be my 4th and 5th underquilts, so I don't expect perfect construction, and want a comfortable margin of error. If during controlled testing I can make it to 0° or below with either of them (if I get a 0° to play in) that will be icing on the cake. Toasty at 20 is the goal. Many thanks for the advice!